Dry drugs such as powdered or lyophilized drugs are typically stored in sealed vials. In practice, the drug is accessed shortly prior to use by rupturing or piercing the seal. A solvent solution such as saline is then introduced into the vial to reconstitute the powdered or lyophilized drug. Once reconstituted, the drug solution is extracted from the vial for use.
Some prior art vials of powdered or lyophilized drugs include a pierceable membrane secured across the open top of the prior art vial. The membrane is normally pierced by a needle in communication with the solvent. However, care must be taken to avoid the separation of membrane fragments when the seal is pierced, as these may be accidentally delivered to the patient. Typically, these seals must be pierced each time access to the solvent is desired, heightening the problems associated therewith.
Other prior art vials include rubber stoppers that are either removed from or urged into the vial when delivering the solvent for reconstituting the drug. While in general these assemblies work well to safely store the drug prior to use, one drawback of these stoppers is that they cannot be accessed after they have fallen into the vial. Hence, the vial cannot be resealed employing the stopper originally provided. Accordingly, the structure of these prior art vials is not readily adapted to a vial capable of repeated opening or closing. Where a practitioner may not desire or need to administer the entire dose of reconstituted drug held in the vial, the vial would typically need to be resealed against the ambient environment to preserve the sterility of the drug remaining in the vial.
The stopper employed with a particular drug is typically formulated from a material compatible with the drug held in the vial. While the stopper normally poses no harm to the safety of the reconstituted drug, there may be a perception--however flawed--that the presence of the stopper in the interior of the vial somehow adversely affects the drug held therein. Also, there may be the perception that the presence of the stopper in the vial may interfere with the subsequent flow of the drug solution.
One way to address the foregoing concerns is to employ a membrane construction as part of the transfer assembly. The membrane may feature one or more fluid openings which are selectively operated by a practitioner by the attachment or removal of a medical delivery device to the transfer assembly. In such assemblies, the membrane is configured for self-sealing operation interim repeated uses of the vial. However, during use a slight over-pressure may build within the vial. The slight over-pressure may cause some splashing of medicament from the vial as the medical delivery device is removed from the transfer assembly.